When `@module` attribute is missing, what should a processor do?

[martindholmes]

The @module attribute on <*Spec> or <attDef> elements is optional, but it's not clear what should happen when a processor encounters an element without this attribute in a base ODD. In this situation, the current Stylesheets ignore the element entirely; so, for example, if you remove module="core" from the TEI <p> element's <elementSpec> in p5subset.xml, there is then no <p> element specified in the output schema, nor are there any references to it.

This is definitely one approach, but as far as we can see, it's not documented anywhere. The problem is rarely encountered because most customization ODDs are processed against p5subset.xml, and p5subset.xml does not omit any @module attributes, But as ODD chaining becomes (we hope) more common, we need a definite stance that is clearly documented.

Options are:

1. Make @module required. This is slightly backwards-incompatible, but the only fallout is that people's ODD files become more precisely specified.
2. Decide and document that the removal of all such specifications is the correct behaviour for a processor (and make processors flag this with warning messages, perhaps).
3. Decide that this behaviour is wrong, and that some other behaviour is appropriate, and that such specifications should be silently included. We (@sydb and @martindholmes) consider this to be a very bad idea, because it would prevent any customizer from excluding such elements using <moduleRef>; instead, such elements would have to be explicitly deleted through the use of their @ident.

[martindholmes]

Council at the FTF today decided to go for the first option: require @module, but of course with a deprecation period and clear documentation. This does not solve all the dilemmas around modules, but it does make it possible for us to provide useful error messages and to explain more clearly that an element belongs in one and only one module, and that module must be specified when declaring or modifying an element (or a class).